Sink



FIG. 1 is a perspective view of a sink showing my new design;

FIG. 2 is a rear perspective thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line showing portions of the sink forms no part of the claimed design. 

CLAIM The ornamental design for a sink, as shown and described. 